Growth features for pink salmon <i>Oncorhynchus gorbuscha</i> in generations with different survival rate in the marine period of life

Abstract

There is believed in classical fishery ichthyology, that slower growth can be a reason for decreasing of fish abundance. A sharp decrease occurred recently in the pink salmon abundance on the eastern coast of Sakhalin Island that inspired this study of growth in the pink generations with different survival during the marine period of life. The growth rates were determined using the scale measurements for the pink salmon returned to the southeastern coast of Sakhalin in 2005-2018. The growth parameters (length increments, variability and asymmetry of size composition) were compared with the survival rate of corresponding year-classes. Slower growth coincided with lower survival for feeding fry only, i.e. in the early marine period of pink salmon life. So, the hypothesis is not confirmed about a «crucial size» for salmon juveniles that must be reached until the end of summer-autumn feeding to survive during wintering. That means that previous estimations of size-selective mortality of pink juveniles are not realistic because of both inadequate samplings and reconstructions in size composition during the juveniles growth.